1. Field of the Invention
The present invention relates to an apparatus for positioning reinforcement members a distance from a surface and, in particular, a method and an apparatus for locating reinforcement bars a specific distance from a surface of a mold or from a graded soil surface.
2. Description of Related Art
Many types of concrete structures, such as slabs or floors, often include reinforcement bars which are used to increase the strength and integrity of the structure. The reinforcement bars are typically arranged in rows or grids within a form into which concrete is poured. The intersection of the bars in the grid are often tied together so that the bars remain in the desired position while the concrete is being poured. Spacers are conventionally used to support and position the reinforcement bars a desired distance from the concrete form. The spacers allow the reinforcement bars to be fully encased by the concrete and the spacers allow the reinforcement bars to be positioned at a generally uniform depth within the concrete structure.
A spacer that is placed on the floor of the mold or on a graded soil surface is often referred to as a high chair or bar chair. High chairs are specifically designed to hold reinforcement bars at a predetermined distance above the floor of the mold or soil surface. This allows the reinforcement bars to be positioned at a predetermined distance from the upper and lower surfaces of the concrete structure. Proper spacing of reinforcement bars from the upper and lower surfaces of the concrete structure, according to known engineering and architectural specifications, increases the strength and integrity of the structure. Additionally, proper spacing of the reinforcement bars from the outer surfaces of the concrete structure is beneficial because it helps prevent moisture from reaching the bars, which causes deterioration of the bars.
Spacers used to position reinforcement bars within a concrete form are known. For example, U.S. Pat. No. 3,255,565 issued to Menzel discloses a tubular spacer with a base portion and a top portion. The base portion supports the top portion a predetermined distance above a concrete form, and the top portion includes a pair of diametrically opposed apertures for receiving and gripping a reinforcement rod. The base portion is supported by three or four vertically extending legs which hold the base above the surface of the mold.
Another known spacer is disclosed in United Kingdom Patent No. 1,276,874 issued to Dale, et al., which consists of a tube or pipe having multiple pairs of diametrically opposed holes which are drilled or punched through the side wall of the tube. Each end of the tube is supported by four thin legs which are spaced apart by four notches or openings. The tube has a constant diameter and is constructed of a rigid, plastic material. The holes or notches allow a single bar to be positioned at a specific height, or two or more bars to be located at different heights, relative to a given surface. These bars may be positioned either parallel or perpendicular to each other. This device allows concrete to flow into the spacer only through the openings for the reinforcement bars.
Yet another known spacer for supporting concrete reinforcement rods is disclosed in Canadian Patent No. 1,186,162 issued to Hewitt, et al. The spacer has a frusto-conical or tapered tubular body with two pairs of troughs or cut-outs on both the upper and lower surfaces of the spacer. This causes the spacer to be supported by four narrow legs. This device also allows concrete to flow into the spacer only through the openings for the reinforcement bars.
Conventional spacers are often constructed at several different standard heights because reinforcement bars are frequently spaced at different heights according to the type of structure to be formed. Disadvantageously, this requires spacers of numerous different sizes be constructed. Additionally, if spacers of a non-standard height are required, the spacers must be specially constructed or conventional spacers must be modified to the desired height. Further, because large construction projects frequently require hundreds or even thousands of spacers of different heights, large storage areas of different sized spacers are required. The burden and expense of storing and transporting hundreds or thousands of known spacers of different sizes is great.
Additionally, when the rows or grids of the reinforcement bars are being positioned or when the concrete is being poured into the form, for example, construction workers frequently step on the bars and/or spacers. Conventional spacers, especially those spacers constructed from metal rods, often collapse or deform under the added weight and stress. The deformed or broken spacers must then be replaced, which is often time consuming and awkward, otherwise the reinforcement bars are incorrectly positioned within the concrete structure.